The Effect of Extruder Mechanical Shear and Temperature on Aquatic Feed Pellets Micro Structure and Feed Quality

Abstract

Extrusion as new technology in aquatic feed producing need to understanding the extruder advantage and parameters effect because extruder is sensitive machine ,the production and quality clearly depend on many physical and mechanical parameters, the most affecting physical factor is the feed formulation and the most affecting mechanical factors is the extruder shear properties screw profile (high or low shear) and extruder zones temperature specialist die zone temperature all this factors judging the extruder performance and product quality. The study focuses on study the effect of extruder shear, (high or low shear), die zone temperature of 105, 120, 135 and 150 C o and tow kind of feed formulations (sinking and floating formula) on extruder performance and product quality. The results reported that for producing sinking feed, the optimum parameters at using low shear screw profile and control the die zone temperature at 105C o , the obtained results were 4.911Mg/h production rate, 98.54% sinking pellets percentage, 0.56 m/s sinking velocity, 1.03 expansion ratio, 561,11kg/m3 pellets bulk density and 63% sinking pellets water stability after one hour. For producing floating fish feed the optimum parameters at using high shear screw profile and 135Co die zone temperature, the obtained results were 3.636Mg/h production rate, 97,34% floating pellets percentage, 472min pellets floating time, 1.69 expansion ratio, 383.26 kg/m3 pellets bulk density and 100% floating pellets water stability after one hour. The electronic scanning images explicated the obtained data by measuring the void cells dimensions and the gelatinization degree.